摘要
长江与黄河沉积物的稀土元素（ＲＥＥ） 组成特征不同。长江沉积物ＲＥＥ 含量较高， 元素含量变化也大于黄河样品； 球粒陨石标准化模式表明长江沉积物的（Ｌａ／ Ｌｕ） Ｎ 、（Ｌａ／Ｙｂ） Ｎ 、（Ｇｄ／ Ｙｂ） Ｎ 的值也相应地比黄河沉积物中的高１０ ％ 左右，分布曲线均呈明显的右倾状，轻重稀土分馏明显，相对富集ＬＲＥＥ，且长江样品比黄河样品更富集ＬＲＥＥ，但Ｅｕ 亏损不及黄河样品；两者的北美页岩标准化曲线均呈平坦稍右倾状，具弱Ｃｅ 亏损，Ｅｕ 异常不明显。黄河中游黄土的ＲＥＥ 组成及流域物理风化决定了黄河沉积物的ＲＥＥ 特征；而长江流域复杂的源岩与较强的化学风化控制了长江沉积物的ＲＥＥ 组成特点。长江与黄河沉积物ＲＥＥ 组成特征与世界其他河流沉积物ＲＥＥ 特点一致，它们也可作为河流入海物质组成代表。相对长江沉积物而言，黄河沉积物ＲＥＥ 分布模式与上陆壳的更为相近，可用来示踪上陆壳平均组成。
REE composition in the Yangtze river sediment is different from that in the Yellow river sediment. REE concentrations in the Yangtze river sediments are relatively high, especially LREE and MREE contents are much higher than the corresponding values in the Yellow river sediments, and variations of REE concentrations of the Yangtze river samples are also larger than those of the Yellow river samples. Chondrite normalized patterns show that the Yangtze river sediments have higher (La/Lu)N,(La/Yb)N,(Gd/Yb)N values than those of the Yellow river sediments with relative deviation about 10%.The fractionation patterns are right declined, and LREE are obviously richer. The Yangtze river samples enrich more LREE than the Yellow river samples, Ce and Eu are depleted, especially Eu depletion is quite obvious and more marked in the Yellow river sediments. Both have nearly even and slightly right declined NASC normalized patterns.The LREE are slightly enriched, and Ce depletion and Eu anomalies are very weak, even neglective.REE composition in loess in the middle Yellow river and extensive physical weathering in drainage basins have great influence on REE characteristics in the Yellow river sediments, whereas complex source rock and chemical weathering controlled the REE composition and distribution in the Yangtze river sediments. REE compositions of the Yangtze and the Yellow river sediments can be used as indicators of matter entering sea of rivers in the world. The Yellow river sediment has similar REE composition to the upper continental crust(UCC), so it can also be used to trace the UC composition.
出处
《地球化学》
CAS
CSCD
北大核心
1999年第4期374-380,共7页
Geochimica
基金
国家自然科学基金!(编号:49676288)
国家教育部同济大学海洋地质开放实验室资助
